DRIVERS:

• Loading Board Drivers
• Attenuator Drivers

LOADING BOARD DRIVERS:

You may want to keep the DEMO.ADC driver here until you have checked out some of its features, since it can function with the STIM3A Advanced Stimulus Signal Generator to simulate analog and digital outputs, whereas some real boards may lack certain output capabilities. Plus, it does not count against Daqarta's 30-session free trial period whenever it is in use, and can extend the trial period indefinitely, including use of STIM3A, after that limit.

When you are ready to install a "real" board driver, just replace the DEMO.ADC line with the one appropriate for your board. First find the appropriate driver name, based upon the type of board you have. Current drivers (all with the .ADC file name extension) are shown below:

NOTE:
These Web links go directly to the respective board help systems. When Daqarta is running, however, only the installed board help system is available, via CTRL-H from the Board menu. See also "Viewing Driver Help Without a Board" below. Go to the Download Options page to actually download drivers.

 DEMO        Default driver, no board required

 ESS         Boards using ESS chips, especially
             ES1868.

 SB16        Creative Labs Sound Blaster 16/32/64 series
             including PnP models.  Full duplex support
             allows STIM3A Stimulus Generator use.


 SBPRO       Creative Labs Sound Blaster Pro (8-bit)

 SB8         Creative Labs Sound Blaster (8-bit)
             DSP version 2.xx only.
             Version 1.xx not yet supported.

 THUNDER     Media Vision Thunder Board

 DAS16X      DAS-16, DAS-16F, DAS-16G1, DAS-16G2,
             DAS16, DAS16F, DAS16/330, DAS16/Jr, etc.
             from Keithley Metrabyte, Computer Boards,
             CyberResearch, etc.

 DAS20       Keithley Metrabyte DAS-20

 DAS8X       Keithley Metrabyte DAS-8, DAS-8/LT,
             DAS-8PGA, DAS-8PGA/G2, and DAS-8/AO.
             Computer Boards (CIO-) DAS08, DAS08-PGL,
             DAS08-PGH, DAS08-AOL, and DAS08-AOH.
             CyberResearch CYDAS 8, CYDAS 8PGL,
             CYDAS 8PGM, CYDAS 8PGH, CYDAS 8AOL,
             CYDAS 8AOM, and CYDAS 8AOH

 DAS8JR      Computer Boards (CIO-) DAS08/Jr,
             DAS08/Jr-AO, DAS08/Jr/16, and
             DAS08/Jr/16-AO.
             CyberResearch CYDAS 8JR, CYDAS 8JRAO,
             CYDAS 8JRHR, and CYDAS 8JRAOHR

 DT2821      Data Translation DT2821 family, including
             DT2823, DT2824, DT2825, DT2827, DT2828,
             DT2829, DT21-EZ, DT23-EZ, and DT24-EZ.

 LPTX        Data acquisition / stimulus generation with
             a standard LPT printer port, using simple
             hardware you can build yourself... from
             just a few resistors, to a small multi-chip
             circuit board.  Includes theory, design,
             and general printed circuit fabrication
             instructions.  Perfect for lab or
             classroom.

If your board is not included here, consider if it may be a "clone" of one of these. The "industry standard" DAS-16 and DAS-08 boards, for example, were originated by Keithley Metrabyte but have been widely cloned and enhanced by makers such as Computer Boards and CyberResearch. Among sound cards, many suppliers claim "Sound Blaster compatible"... and some of their boards actually are!

Daqarta requires boards to be "hardware", "register", or "low-level" compatible... they must look just like the target board for all register operations. This is a fairly stringent requirement.

However, many manufacturers claim compatibility even when their product is completely different. They supply drivers to replace those of the target board, intercepting high-level function calls from programs and translating them to the relevant low-level routines needed. Daqarta can't use these drivers, however, since they only support certain basic functions, and even those are often not well suited for the kind of operations needed here. Daqarta makes no attempt to conform to any high-level function protocol. Compatibilty is a nice goal, but not when it requires you to put tractor tires on your race car!

Daqarta drivers also contain their own control menus and processes, as well as context control and invocation of their own Help systems. Filenames with the same first part as the driver name but an extension of .HLP are Help files for those drivers. For example, SB16.HLP is the Help file for the SB16.ADC driver.

Boards often have jumper-selectable parameters such as base address, Interrupt Request (IRQ), and DMA levels. You will need to tell the driver which ones to use if they are not the same as the defaults built into the driver. Parameters are given on the configuration file line after the driver name, and are typically in the format X:n where X is a letter to identify the parameter and n is the value to set. If the value is given in hexadecimal notation, precede it with 'h', as in A:h220 to set the base Address to 220h.

VIEWING DRIVER HELP WITHOUT A BOARD:

    SB16.ADC    A:0

With the A:0 parameter, the driver will appear to load normally but no hardware-specific operations will take place. You can activate the Board option and bring up the Board Control Menu. Now CTRL-H will enter the driver Help system, or CTRL-? will provide context Help for the menu item at the cursor location. You can move the cursor to any menu item just as if the driver were really active, but you will not be able to change any of the values or states... hitting ENTER will have no effect. If the driver has alternate menu pages, the CTRL-Pg keys will move to them as usual. Submenus, however, can not be activated due to the disabled ENTER key.

To see a short summary of the board's parameters and defaults, use ALT-H to bring up a list of all resident drivers. The Board driver will be first. With the Help cursor highlight on that line, hit ENTER to see a one-page summary for that driver.

When the board driver has been disabled with A:0, the trace will continue to show Virtual Source operation. Other menus like Trigger will behave as though Board had not been activated and Virtual Source was still in effect by default.

In addition to allowing you to access setup information for your board and driver, this A:0 disabled mode can be used to help you decide which board to buy if you don't already own one. You can see what features can be controlled by each board menu, and read about performance and specifications in the Help system.

ATTENUATOR DRIVERS:

An attenuator is essentially a volume control with discrete, calibrated steps, usually in dB (decibels). Its main use with Daqarta is for precise and repeatable control of stimulus levels, whether those signals are generated externally, or internally via the STIM3A Advanced Stimulus Signal Generator.

Like all digital signal generators, STIM3A can provide limited control of signal levels by simply scaling the numerical values that make up the waveform, using its Level controls. The problem with this approach is that as levels get smaller, less bits are used to represent the signal. For example, to get the equivalent of 48 dB of attenuation, the Level control would have to be set to 0.40%. The 16-bit values that STIM3A uses internally would then be effectively scaled to only 8 bits for output... assuming the output DACs were 16-bit devices to begin with.

With 8-bit DACs the output range would be less than a single bit... making it essentially a rectangular wave! Even with the 12-bit DACs common on lab-type boards, the output would only cover a 4-bit range. This means a sine wave would have only 16 different steps, which is pretty poor fidelity... and auditory tests commonly require much more than 48 dB of attenuation.

So the best option is to generate the signals using the full range of the DACs, and attenuate them separately.

Daqarta allows you to use a separate Sound Blaster 16/32/64 sound card as an attenuator (ignoring its data acquisition capabilities). This will work with the STIM3A Output dB control to give 0.01 dB resolution over the full range.

There are also drivers for two "legacy" laboratory-type programmable attenuator systems from Tucker-Davis and Wilsonics.

At first glance, it may seem redundant to use a laboratory-type board for acquisition, and a separate Sound Blaster just to provide attenuation. Since the Sound Blaster contains its own built-in attenuators, and the normal SB16.ADC driver can control those completely, why not do everything with the Sound Blaster and skip the lab-type board?

The main reason is that Sound Blasters can only generate or record signals in the normal audio range. They don't allow sample rates above 48 kHz, for either input or output. So if you need to work at higher frequencies, you will need a lab-type board.

Even if you only need to acquire data at 48 kHz or less, there is a problem if you need to generate stimuli at frequencies above about 20 kHz: The Nyquist limit applies to generated signals as well as to acquired signals, so you can't generate anything with a frequency above half the sample rate... and even at frequencies quite a bit lower, the waveform may have rather few samples per cycle.

But lab-type boards allow you to use the Stimulus Factor option to provide stimulus oversampling with STIM3A. So even if you are using a low acquisition sample rate, you can use a very high stimulus sample rate for good waveform fidelity at high output frequencies.

Note that the ATN-SB16 module uses only the mixer chip of the Sound Blaster, bypassing the digital signal processor completely. This results in much better high-frequency response, often up to 100 kHz or more depending upon the model and output used (Line output is better than Speaker). The Tucker-Davis and Wilsonics legacy systems were typically limited to about 20 kHz unless they were special orders.

    ATN-SB16.ATN    Creative Labs Sound Blaster 16/32/64 series
                    including PnP models and ViBRA 16X.  Two
                    independent channel controls, plus Line /
                    CD selection.  0 to 138 dB and Off in 2.0
                    dB steps (0 to 90 in 1.5 dB steps for
                    ViBRA).  Compatible with STIM3A
                    Output dB
                    control, giving 0.01 dB resolution over the
                    full range.  Adjustable 0 dB reference.
                    For all new systems.

    TDT1.ATN        Tucker-Davis PA3 Programmable Attenuator.
                    Only the System 1 version using the IM3
                    Interface Module is supported.  Requires
                    a separate 8255-type parallel port for
                    control.  Controls up to 4 PA3 modules,
                    0 to 99 dB and Off in 1 dB steps.
                    (Legacy only.)

    WILSONIC.ATN    Wilsonics PATT Programmable Attenuator.
                    Supports either direct parallel control or
                    GPBA (General Purpose Bus Adaptor)
                    interface.  Requires a separate 8255-type
                    parallel port for control.  With GPBA,
                    controls up to 4 PATT modules.  0 to 99 dB
                    and Off, in 1 dB steps. (Legacy only.)

Use the TDT1 or WILSONIC only if you already have that legacy hardware... these devices are no longer being made. New systems should use the ATN-SB16 where possible. Besides better high-frequency response, the SB16/32/64 systems are much more convenient to install (they don't require separate rack mounts, bus interfaces, or power supplies), and they are much less expensive and much more readily available than the legacy systems ever were.

The downside of Sound Blaster use is that the noise level may be a bit higher, not only because of the wider bandwidth, but also because these are consumer-grade products, and because they are installed inside the computer, where electrical noise is high. Nevertheless, they should be adequate for the vast majority of uses, including auditory threshold measurements.

All of these drivers allow you to specify the preferred sense of their controls when scrolling, with the default being that up gives increasing output level. The maximum output will be at 0 dB, and all lower outputs will show as negative dB.

Optionally, you can use a configuration parameter to specify that up gives increasing attenuation. The maximum output is still shown as 0 dB, but as you scroll up the output levels decrease and the dB values are positive and increasing.

In either case, you can always enter a dB value directly... the sign is ignored. Likewise, all systems always start at maximum attenuation, for safety.